While partisans try to diminish the role radical Islam plays in fueling global terrorism, a new report released by the Institute for Economics and Peace (IEP) finds that “The most prolific religious terrorist groups are almost exclusively Islamic.”

The IEP’s 2012 Global Terrorism Index rates 158 countries related to terrorism from 2001-11 using data from the Global Terrorism Database (GTD), which is collected and collated by the University of Maryland’s National Consortium for the Study of Terrorism and Responses to Terrorism (START).

“The rise of religious extremism is well-documented,” the report says, with Islamic groups being the most prolific. It notes a decrease in attacks from nationalist/separatist groups since 2008, but adds that some Islamist groups like “the Taliban or Lashkar-e-Taiba (LeT) have nationalist/ separatist aspirations.”

The nationalist characteristics of such Islamic terror groups do not, however, negate their violent Islamist nature.

For such Islamist/nationalist groups, “‘True’ Islam only exists when it is the primary source of governance, manifest today by the implementation of a fundamentalist interpretation of Islamic law,” the report says. “It supersedes tribe, or nationality today, it is to be defended everywhere it exists, and when it exists it is an ascendant force. According to this logic, in the current moment of extended crisis Muslims are duty-bound to follow the example of the Prophet and emigrate from places of persecution to a place where they can fight on behalf of ‘true’ Islam. If they cannot make that journey, they are to fight where they live.”